1. Field of the Invention
The invention relates to a load distribution control system, including a plurality of computers, for having the computers execute jobs by distributing loads for the computers, and also relates to a load distribution control method.
2. Description of Related Art
Recently, various computer load distribution techniques have been suggested (see JP-A-1049504, JP-A-11-3323, and JP-A-10-334057). As computers have achieved high performance, when controlling load distribution, the processing time (Turn Around Time [TAT]) spent to obtain the processing results for an executed job varies considerably depending on whether jobs to be executed by computers are distributed well or not. Also, since workstations (WS) have become widespread, control parameters for load distribution have become complicated and it is difficult to efficiently distribute loads.
On the other hand, because the scale and functionality of applications have advanced, the processing time required for a computer system to execute an application program and obtain results has increased rapidly. An environment that allows stable job execution is required for all jobs that application programs intend to fulfill, but such an environment has not been realized. When causes of abnormal job termination prior to the completion of jobs are analyzed, it is found in many cases that a disk, which is a data storage means, has a shortage of capacity, and an operator makes a mistake and instructs the application to select incorrect data. Also, regarding a CPU where “I/O Wait” for a disk has occurred, the usage rate of that CPU has decreased considerably in many cases.
In order to control the load distribution described above, JP-A-10-49504 adopts a configuration where jobs are stored and kept as single jobs or job groups hierarchically on the basis of load distribution unit, and the jobs stored and kept in any hierarchy are transferred from a job registration machine to a job execution machine on the basis of that load distribution unit. However, sufficient attention is not paid to disk optimization or stabilization of program processes.
JP-A-11-3323 adopts a configuration where the load status is intensively monitored and managed, and the computer having the lowest load is selected based on the result of that monitoring and managing, and the selected computer is made to execute a job. Disks can be excluded from machine candidates that can execute the job by using a parameter. However, if excluding the disks by using the parameter is considered, the operation rate for the computers will decrease.
Furthermore, JP-A-10-334057 adopts a configuration where resources using batch job properties are classified and a batch job execution server with a resource load status that meets the relevant classification is dynamically decided based on information from a batch job execution server load status acquiring subsystem. However, sufficient attention is not paid to disk optimization or stabilization of program processes.
In other words, when an application program for RAID logical designing processes mass data by means of conventional load distribution techniques, the processing of a job to execute the application program sometimes becomes unstable, the job processing time increases, and a computer's access performance to the storage unit where the relevant data is stored sometimes decreases.
There is also a technique based on the idea of “DLCM” for effectively utilizing storage resources by distributing data to be accessed by a computer to a plurality of storage units. If data necessary for job execution does not exist in the storage unit accessed by the computer, there is the possibility, even in the environment where load distribution is realized, that an I/O access by the computer to the storage unit may enter the wait state or become an error. The same can be said about the case where the storage unit accessed by the computer does not have the necessary storage capacity for completing a job.
Accordingly, it is an object of the invention to provide a system, including a plurality of computers, for distributing loads on the computers wherein the access performance of the computers to a storage device, where data is stored, is enhanced and the computers thereby efficiently process jobs by executing an application program and where the TAT can be shortened.